How to Make It
In a blender, puree the pineapple until smooth; you should have 1 cup.
Using a 2 1/2-inch biscuit cutter, stamp out 8 rounds from the slices of pound cake and transfer the rounds to a baking sheet. Scoop the ice cream into 8 balls, flatten the bottoms and place them on the pound cake rounds. Freeze until very firm, at least 30 minutes.
In a standing electric mixer fitted with the whisk, combine the pineapple puree with the Simple Syrup, egg white powder and xanthan gum and beat at high speed until stiff peaks form, about 5 minutes.
Preheat the broiler and position a rack 6 inches from the heat. Transfer the pineapple meringue to a piping bag and, working quickly, pipe it all over the ice cream and pound cake, covering them completely. Broil the Alaskas until golden, about 1 minute, turning the baking sheet as needed. Transfer the baked Alaskas to plates and serve right away, garnished with lime zest and mint leaves.
Egg white powder is available at health food stores and most supermarkets.